JPH11351463A - Joint made of cast iron for connecting metallic equipment of different kind - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the generation of rust caused by the difference in the ionization tendency by very thinnly coating the threaded surfaces of the joints with a synthetic resin adhesive in advance, and applying an adhesive for sealing between a lining layer and a relay screw continuously from the synthetic resin adhesive. SOLUTION: When this is applied to the elbow-type joints, a lining layer 2 of synthetic resin is formed on the inner surfaces between both threaded parts 3a, 3b of the joint bodies 1 made of malleable cast iron and having the threaded parts 3a, 3b on both ends, a tube end corrosion-proof core 4 is inserted into the threaded part 3a at one end and a relay screw 5 is inserted into the threaded part 3b at the other end. The tube end corrosion-proof core 4 is formed by the injection molding of the synthetic resin, and engaged with the threaded part 3a by a male screw 9 formed at a depth end, and an O-ring 11 is fitted on an annular groove 13 formed on an outer peripheral surface of its point. Then the corrosion-proof core 4 and the lining layer 2 are closely contacted with one another, an adhesive 7 is packed in a recessed part therebetween, and the relay screw 5 is screwed into the threaded part 3b through an adhesive 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast iron used not only for connecting pipes but also for connecting dissimilar metal equipment having a smaller ionization tendency than iron, such as a water tap and a valve made of copper alloy. Related to pipe fittings.

[0002]

2. Description of the Related Art As a means of preventing corrosion of cast iron pipe joints for connecting dissimilar metal appliances, there are means for preventing rust due to contact with dissimilar metal appliances in addition to means for preventing rust due to contact with water. That is, since these devices are usually made of a copper alloy having a lower ionization tendency than iron, an oxidation / reduction reaction proceeds during that time, and a joint having a high ionization tendency rusts at the contact portion of the threaded portion by oxidation ( (So-called galvanic corrosion occurs.) Therefore, measures are taken to electrically cut off the gap so that electrons do not move.

As shown in FIG. 3 (also FIG. 4), a lining layer 32 is formed on the inner surface by injection molding of a synthetic resin such as hard vinyl chloride.
A connection port 38 with the lining steel pipe is formed integrally with the lining layer 32 in the screw portion 33a at one end. However, in order to maintain the strength for supporting the connection port 38, the lining layer 32 is formed to be excessively thick in terms of cost.

At the other end of the joint body 1, as shown in the figure, a threaded portion 33b is formed short, and a threaded portion 33c is formed in addition to the lining layer 32, on which a device such as a water tap is provided. It is screwed in and connected. However, in connection work of dissimilar metal equipment, the screwing of the resin screw portion
When it does not reach c, the threaded portion 3b of the joint body is exposed to water and rust is promoted.

[0005] Even if the screwing is deep enough, the resin screw portion 33c
The sealability was not always maintained at the position (1). In addition, because contact with dissimilar metal equipment is cut off,
Corrosion prevention measures are taken for the difference in ionization tendency only in this part 33c, but the screw part 33b is in direct contact with the screw part 33b, so the measures are incomplete.

As a means for solving this problem, as shown in FIG. 4, a female screw (or male screw) relay screw 35 of the same material as a dissimilar metal is screwed into the screw portion 33b at one end as an intermediary. An insulating coating 36 is applied to the relay screw 35 in advance to cut off electrical contact with the joint body 1, but the relay screw 35 is broken and damaged by an external force received at the time of screwing in or after, so that the relay screw 35 does not function. For this purpose, a protective layer 3 of an adhesive containing cement is further provided between the joint body and the threaded portion 33b.
7 are interposed.

However, in order to protect the insulating coating 36, it is necessary to make this protective layer 37 thicker, and it also serves as a seal and a sticker. Since looseness and play are apt to occur in the connection, there has been a problem that the center axes are displaced or tilted when the dissimilar metal appliances are mounted. In addition, since it is completely electrically insulated, it is not possible to use an electric deicer that operates by energizing the pipe when the pipe is frozen in a cold region. In addition, naturally, there is a problem that the cost is increased by the insulating coating 36.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention has a cost-effective structure and is capable of effectively preventing rust from occurring without any inconvenience. Aimed to provide.

[0009]

In order to achieve the above object, the present invention relates to a threaded malleable cast iron pipe joint, wherein the joint body has a synthetic resin lining on an inner surface between threaded portions. A cast iron pipe for connecting dissimilar metal appliances, in which a layer is formed and a relay screw of a material similar in ionization tendency is screwed into the screw part on the side connecting the dissimilar metal appliances for direct screwing of the dissimilar metal appliances. At the joint, a very thin synthetic resin adhesive is interposed between the threaded surfaces and filled with a sealing adhesive between the lining layer and the relay screw continuously with the adhesive. Thus, a pipe joint made of cast iron was constructed.

[0010] According to the above-mentioned cast iron pipe joint for connecting dissimilar metal appliances, dissimilar metal appliances such as water taps and valves are screwed into the junction screw and connected. Due to the intervening adhesive, the oxidation and reduction reactions are sufficiently prevented even if the electrical insulation is incomplete, and as a result,
The generation of rust on the thread is prevented. In addition, since the adhesive is filled between the joint body and the lining layer continuously, the state where the joint body does not come into contact with water stably is maintained. Therefore, if the entire inner surface of the joint body does not come into contact with water as described below, it is possible to ensure the anticorrosion means.

That is, a pipe end anticorrosion core is screwed into the screw portion on the side to which the lining steel pipe is connected for connection with the inner surface thereof, and an adhesive is provided between the lining layer and the pipe end anticorrosion core. Is more effective in achieving the object.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the connecting screws 5,
As for the material of No. 6, if it is a metal which is comparable in ionization tendency to dissimilar metal appliances such as hydrants and valves,
It is not necessarily limited to a copper alloy.

Regarding the form of the joint body 1, not only the elbow type and the socket type as shown in the embodiment, but also
For example, it may be implemented in other types such as teeth.

Although an adhesive 8 is interposed between the threaded portion 3b of the joint body 1 and the relay screws 5 and 6, the adhesive 8 is formed as a thin layer sandwiched between regular screwing which normally meshes. , Which makes the screwing accurate and the axes coincide. Also, it is firmly fixed by adhesion.

[0015]

As described above, according to the cast iron pipe joint for connecting dissimilar metal instruments of the present invention, the difference in ionization tendency can be attained only by applying an adhesive and then screwing a relay screw. Rust can be prevented, so it is easy to manufacture and suitable for inexpensive provision.In addition, since the relay screw can be attached accurately and firmly, there is no inconvenience that the connection of dissimilar metal equipment is shifted or inclined. Also, there is an excellent effect that the adhesive between the lining layer and the lining layer is accurately covered with the continuous adhesive.

The entire inner surface is completely covered by forming the lining layer, mounting the pipe end anticorrosion core, and filling the adhesive (Claim 2), so that the anticorrosion effect is further enhanced.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an example in which the present invention is implemented as an elbow type. A malleable cast iron joint body 1 having screw portions 3a and 3b at both ends is provided with an inner surface between the two screw portions 3a and 3b. A lining layer 2 made of a synthetic resin is provided, and a pipe end anticorrosion core 4 is screwed into one end of a screw portion 3a, and a relay screw 5 is screwed into a screw portion 3b of the other end.

The pipe-end anticorrosion core 4 is injection-molded with a synthetic resin, has an extremely narrow male screw 9 formed at the base end on the inside, and has a short cylindrical end, and is screwed into the screw portion 3a. Plugged in. An annular groove 13 into which the O-ring 11 falls is provided at the end, and an annular flange 15 is protrudingly provided on one side outside the annular groove 13. The annular flange 15 is bent by a lining steel pipe to be screwed into and covers the O-ring 11.

As described above, since the pipe end anticorrosion core 4 is separate from the lining layer 2 and is directly connected to the joint body 1, the lining layer 2 can be rationally irrespective of the support of the pipe end anticorrosion core 4. It is formed thin. And this pipe end anticorrosion core 4
Is brought into close contact with the lining layer 2, and the recess formed therebetween is filled with an adhesive 7. This is the joint body 1
From the inner surface to the inner surface of the lining steel pipe is continuously coated without being cut by the resin.

The relay screw 5 is made of a copper alloy like a copper alloy water tap as a dissimilar metal appliance, is a bush type, and is a female screw type into which the water tap is screwed. It has a male screw 17 that is screwed into one screw portion 3b.

When the relay screw 5 is screwed, the adhesive 8 is applied to both or one of the male screw 17 and the screw portion 3b of the joint body 1. In this case, the joint body 1 and the relay screw 5 are electrically insulated, and although not complete, the oxidation / reduction reaction is hindered therebetween, thereby preventing rust of iron.

Further, similarly to the case of the pipe end anticorrosion core 4, the adhesive 7 for sealing is filled between the core and the lining layer 2, and the exposed portion of the screw portion 3b is also filled with the adhesive 7. The adhesive 7 is continuous in the vicinity of the pipe end anticorrosion core 4 and the relay screw 5.

FIG. 2 shows an example of a socket type. Similar to the above embodiment, a pipe end anticorrosion core 4 is connected to a threaded portion 3a at one end of a joint body 1, and a dissimilar metal device is connected to the other end. A nipple-type relay screw 6 is screwed in, and an adhesive 8 is interposed in the screwing of the relay screw 6. The adhesive 7 is filled between both the pipe end anticorrosion core 4 and the relay screw 6 and the inner lining layer 2. Since the relay screw 5 is a male screw type, a valve is mainly connected as a dissimilar metal device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cast iron pipe joint for connecting dissimilar metal appliances showing one embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment.

FIG. 3 is a sectional view showing a conventional example.

FIG. 4 is a cross-sectional view showing a conventional example and enlarging a part thereof by a lead line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint main body 2 Lining layer 3a, 3b Screw part 4 Pipe end anticorrosion core 5,6 Relay screw 7,8 Adhesive

Claims (2)

[Claims] 1. A threaded malleable cast iron pipe joint, comprising:
In the joint body, a lining layer of synthetic resin is formed on the inner surface between the screw parts, and the screw part on the side connecting the dissimilar metal equipment is used for direct screwing of dissimilar metal equipment. In a cast iron pipe joint for connecting dissimilar metal appliances screwed with a relay screw, a very thin synthetic resin adhesive is interposed between the screwed surfaces, and continuously with the adhesive. A cast iron pipe joint characterized by filling a sealing adhesive between a lining layer and a relay screw. 2. A pipe end corrosion-proof core is screwed into a threaded portion on a side to which a lining steel pipe is connected for connection with an inner surface thereof, and an adhesive is provided between the lining layer and the pipe end corrosion-resistant core. The cast iron pipe joint for connecting dissimilar metal appliances according to claim 1, characterized in that: